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By Charlie
#98447
My 1991 S4 is a great car and I like everything about it. Except: At low speed the steering is like my old Mazda mini pickup (which did not have power steering). I drove a '90 S4 recently and the steering was much more "normal."

The catalog shows that the rack is PN 92834701027 with remarks "/LL 91-", or PN 92834701024 with remarks "/LL -91". According to Porsche Atlanta both have been replaced by 928347010CX ($2500). 928Intl has both PNs, but shows 027 as 82-89 and 024 as 78-81 ($600).

My understanding is that later cars got a different rack ratio. It is possible that my car got an earlier rack from a PO.

My question to the oracles: What year did it change? How can I tell which I have for sure? If I have the wrong rack, what are my alternatives?

Thanks in advance all.
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By ROG100
#98546
The upgrade from a 75Bar pump to a 100Bar pump was implemented in 91. So technically your 91 already has the upgraded "easier to steer" setup. The 91+ rack was also different.
However Porsche no longer differentiates between 90 & 91+ racks or PS Pumps.
My advice to my customers is to send us your rack for rebuild so that you get the original 91+ rack back.
With the help of a customer we also have the rebuild kits for the 100Bar pumps.
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By Gary Knox
#98552
This post made me wonder how many 928 owners would be interested in an electric power steering system. I'd wager that if we got 50 people committed to it, an entrepreneur like Roger (or other in the trade) would be interested in developing one!! Hmm, I suspect a fair percentage of the parts might be available.

Hmm, I might even add my name to such a list.

Gary
Last edited by Gary Knox on Wed Aug 18, 2021 3:38 pm, edited 1 time in total.
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By worf
#98561
Let us not forget that the vast majority of 928s are not running around on their original rack but are equipped with a core-exchange unit. So, a rack out of a ‘91 isn’t guaranteed to be a rack out of a ‘91.
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By worf
#98563
Charlie wrote: Tue Aug 17, 2021 9:00 pm It is possible that my car got an earlier rack from a PO.
Highly likely since the OE 91+ racks (if not all 87+ racks) didn’t seem to last more than 10 years before leaking.
Charlie wrote: Tue Aug 17, 2021 9:00 pm How can I tell which I have for sure? If I have the wrong rack, what are my alternatives?
I’m pretty sure there is a “year” stamp on the rack. I’ll see if I can find a picture.
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By Charlie
#98594
Thanks guys. @worf I certainly hope you'll get a chance to eyeball this firsthand.

I would like to get this solidly diagnosed before ordering anything obviously. Is there a different pump needed also perhaps?

Re interest in electric power steering, it depends on how easy it is to get the correct parts. I would like to go back to stock ideally. But for many of these later revisions there is not a very large population of cars to scavenge, e.g. try finding an airbag-dash center console. So maybe some of us will be forced at gunpoint to use a better modern technology. Short version: Could be interested!
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By worf
#98662
So, if I uploaded the 30,000+ pictures of 928 bits that I've taken to the Apple Cloud and let apple's stuff index it do you think it would be able to find picture of "928 steering rack date code?"

Yeah. Me neither.

Unable to provide incontrovertible supporting pictorial evidence and, unusual for me, I have neither suitable 928s located in a convenient position to get good eyeballs on a rack nor a rack sitting on a bench.

I know there's something on the 928 rack somewhere that will provide a good guestimate of what year rack it is.
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By worf
#98664
Charlie wrote: Wed Aug 18, 2021 12:41 pm Is there a different pump needed also perhaps?
Occam's Razor: the pump is the correct pump and the steering rack is a core-exchange from the 'wrong year.' The pumps seem to be pretty bullet proof compared to the racks.

Alternative explanation: your rack isn't functioning properly. But racks seem to have only two mechanical states: working or very-obviously not working. Kinda-working? Not so much.

On the other hand: that '90 you drove... I assume it was at Camp 928? Yes? - that has very, very extensive GB work and has special bits on it that change its behavior in various ways.

We (and buy 'we' I mean 'you' :tongue: ) can look at the ~50 pages of invoice I have for it from Mary for anything power steering related next time you're up here.
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By Charlie
#98747
LOL. That was in fact the '90. The steering was pretty easy at low speeds. Not that there was much of that going on.

All my non-essential activities are on hold until Labor Day, but I will have my car off the ground after that and will try to get a visual on the rack. I'm still interested in looking at that invoice - it must be quite a page-turner.
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By SCX2132
#99425
The early racks have date codes on the tags and in the housing castings. Not sure how long this practice continued.
Image
Image
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By Charlie
#99455
@SeanR Yes it definitely will, and I am, but this was happening with the 225/50-16s also.

@SCX2132 many thanks. Those pics are very helpful - I hope ZF continued the practice through '91.
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By Gary Knox
#100277
There is an interesting thread on the 'other' site with the original post from a guy in Europe who had a 10% smaller pulley built for the pump.

Gary

And another short clip https://www.youtube.com/wa[…]

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Panorama September 2021

great representation ~!